﻿    <p>
      The
      <em>IfcPropertyReferenceValue</em> allows a property value to
      be of type of an resource level entity. The applicable
      entities that can be used as value references are given by the
      <em>IfcObjectReferenceSelect</em>.
    </p>
    <blockquote class="history">
      HISTORY&nbsp; New entity in IFC1.5. Entity has been renamed from
      IfcObjectReference in IFC2x.
    </blockquote>
    <blockquote class="change-ifc2x4">
      IFC4 CHANGE&nbsp; Attribute
      <em>PropertyReference</em> has been made OPTIONAL with upward
      compatibility for file based exchange.
    </blockquote>